It is a known method for the treatment of radioactive waste water (BG 60569) that is first concentrated to an almost dry salt and thereafter treated with alcohols with longer carbon chains. At the treatment of boron acid-containing salts with alcohols, an esterification of the boron acid and alcohol begins. The ester so obtained is treated by a high temperature (above 100° C.) distillation until boron acid is produced.
The main shortcoming of this method is that all the processes are running at high temperatures, using longer carbon chain alcohols and applying ester distillation of boron acid with large heat energy consumption. Basically this process is very complicated and much labor force consuming.
It is also a known method (BG 51265A) for the treatment of radioactive wastes until boron acid salt —Na2B4O7 (borax) containing radionuclides of an environmentally allowed concentration is obtained. The method consists of several stages—concentration of radioactive wastes with different indicators of pH—lower than 4.5 and higher than 8.5, and thereafter mixing the concentrates. Under an appropriate temperature regime, the radioactive waste containing boron acid of a concentration of 15-20 g/l and the borax in an environmentally admissible radioactive isotope concentration, are produced, which is non-radioactive waste. By a suitable technology from the non-radioactive salt—borax, a boron acid solution can be obtained.
An installation additionally presented to this method is for radioactive waste treatment, which includes a reservoir for radioactive wastes with pH lower than 4.5, a reservoir for radioactive wastes with pH higher than 8.5, a reservoir with radioactive wastes with pH between 4.5 and 8.5, evaporators, mixer for the concentrates with different pH, reservoir for correcting additives, crystallizer for borax, filter with adsorbent, reservoir for the concentrated lye, and reservoir for non-radioactive boron acid.
A shortcoming of this method and the used installation is to keep the content of 15-20 g/l non-radioactive boron acid in the radioactive waste subject to further long-term storage. The remaining radioactive waste contains non-radioactive boron acid, which takes up large capacities in the radioactive waste storage facilities, reduces the cement matrix strengths and filling up with salts is decreased; and also allows radioactive isotopes, washing away from the matrix in case of radioactive waste cementation method application. Thus there is a continuing negative effect on the safety during the interment accompanied by an increase of the costs of treatment and the interment.
The known methods for treatment of the liquid radioactive wastes from this background, are directed predominately to the neutralization of the negative effect of the boron acid on the immobilized product, especially during cementing, and there are no other non-radioactive products except water to be separated.